Funding is requested from the National Institutes of Health, Division of Research Resources to equip a shared INTERDEPARTMENTAL CORE FLOW CYTOMETRY FACILITY at the Johns Hopkins University School of Medicine. The primary user group is comprised of 14 investigators in the Departments of Medicine, Molecular Biology and Genetics, Biological Chemistry and Cell Biology and Anatomy, and the Sub-department of Immunology. These investigators are located in the Preclinical Science building complex of The Medical Institutions. Each individual directs an independent NIH-supported research program. There is no flow cytometry facility at this site and existing instruments in other areas of the Medical Institutions are overutilized by other user groups. The amount requested for this facility is $316,445 to purchase a FACStar-plus. This instrument is equipped with a 4 watt argon dye laser and a 5 watt argon ion laser with UV capability to meet the needs of investigators for simultaneous multiple fluorochrome analyses, calcium and RNA measurements, and chromosome sorting. An automated cell deposition unit is necessary for the experiments requiring the cloning of cells, including mutagenized cell lines. A sophisticated MicroVAX computer will provide optimal operation of the instrument, maximize sorting efficiencies, and permit analysis of data already acquired even while the instrument is being utilized for the acquisition of new data. The Department of Medicine is providing 300 ft2 of space in the new Hunterian II Research Building that is easily accessible to members of the primary user group. In addition, the Department of Medicine is providing the salary for the flow cytometer research technician. The INTERDEPARTMENTAL CORE FLOW CYTOMETRY FACILITY will be available on a minimal fee-for-cost basis to the identified primary user group and to other members of the Medical Institutions. The Core Committee, members of which include primary users from each of the participating departments, will make all policy/administrative decisions, provide technical oversight to insure the optimal use of the instrument.